Table 3.
Breast cancer biomarker testing methods, algorithms, and protocols (HER2, ER, PgR)
| Characteristic, n = 57 | No. (%) |
|---|---|
| Methods* and multimethod algorithms† | |
| HER2 | |
| HER2 IHC, reflex test‡ to FISH | 24 (42) |
| Reflex test when result = IHC2+ | 12 (50) |
| Reflex test when result = IHC0, 1+, 2+, and 3+ | 5 (21) |
| Reflex test when result = IHC2+ and 3+ | 3 (13) |
| Reflex test when result = IHC1+ and 2+ | 2 (8) |
| Reflex test when result = IHC0, 1+ and 2+ | 1 (4) |
| Reflex test when result = IHC1+, 2+, and 3+ | 1 (4) |
| Concurrent HER2 FISH and IHC | 17 (30) |
| HER2 FISH | 10 (18) |
| Concurrent HER2 IHC and SISH | 3 (5) |
| Concurrent HER2 CISH and IHC | 1 (2) |
| Concurrent HER2 CISH, FISH, and IHC | 1 (2) |
| HER2 CISH | 1 (2) |
| ER | |
| ER- IHC | 49 (86) |
| ER IHC and RT-PCR | 5 (9) |
| ER IHC and LBA | 3 (5) |
| PgR | |
| PgR- IHC | 51 (89.5) |
| PgR IHC and RT-PCR | 4 (7) |
| PgR IHC and LBA | 2 (3.5) |
| Multibiomarker protocols§ | |
| Retest HER2 for triple-negative cancers|| | 3 (5) |
| Retest HER2 for triple-positive¶ and triple-negative cancers | 2 (4) |
| Retest HER2 for triple-positive cancers | 1 (2) |
* Method, type of technology for testing a biomarker. Italicized choices represent various algorithms for reflexing to FISH test based on IHC results (0, 1+, 2+ and/or 3+). CISH = chromogenic in situ hybridization; FISH = fluorescence in situ hybridization; HER2 = human epidermal growth factor receptor 2; IHC = immunohistochemistry; LBA = ligand-binding assay; PgR = progesterone receptor; RT-PCR = reverse transcription polymerase chain reaction; SISH = silver in situ hybridization.
† Multimethod algorithm, a sequence of methods for testing one biomarker, when multiple methods are used.
‡ Reflex test, confirming equivocal or borderline results by another method.
§ Multibiomarker protocol, a sequence of testing multiple biomarkers.
|| Triple negative breast cancer, HER2-, ER-, PgR-.
¶ Triple positive breast cancer, HER2+, ER+, PgR+.